Agricultural technology improvements over the last decade have resulted in substantial increases in both farm production and productivity. Most of these improvements have been possible by the widespread acceptance of the diesel engine as prime mover for agricultural machinery. Today's “super-tractors”, backbone of the trend towards large farm operations, are all based on highly efficient diesel engines. The decrease in total agricultural fuel consumption over the last 20 years is the best testimony for the agricultural diesel engine.Short term improvements in engine and tractor efficiency should be based on further refinements of known techniques, with added emphasis in combustion control as well as volumetric and mechanical efficiencies. On a longer term, advanced fuel and air handling systems will allow combustion control for improved engine-vehicle matches, resulting in further improvements in the energy efficient use of farm machinery.